1. Field of the Invention
Embodiments relate to a hardmask composition and associated methods.
2. Description of the Related Art
Resist materials used in some lithographic techniques may not provide high resistance to the subsequent etching step to an extent sufficient to effectively transfer a desired pattern to a layer underlying the resist material. A hardmask for a resist underlayer film has been used, for example, in the case when an extremely thin resist material is used, a substrate to be etched is thick, a large etching depth is needed, and/or the use of a particular etchant is required depending on the type of substrate.
For better resolution in most lithographic processes, an antireflective coating (ARC) material may be used to minimize the reflectivity between a resist material layer and a substrate. However, the similarity in basic composition between the ARC and the resist material layer may result in poor etch selectivity between the ARC material and the patterned resist layer. Accordingly, consumption of portions of the resist layer may be inevitable during etching of the ARC after patterning, thus requiring further patterning of the resist layer in the subsequent etching step.
A resist pattern may be used as a mask to process a substrate, e.g., a silicon oxide film. Miniaturization of circuits has resulted in a reduction of the thickness of resists, making it difficult for the resists to act as masks. As a result, processing of oxide films without any damage may be impossible. According to a process to overcome these problems, a resist pattern may be transferred to an underlayer film for processing an oxide film, followed by dry etching the oxide film using the pattern-transferred underlayer film as a mask. In this process, since the etching rate of the resist may be similar to that of the underlayer film for processing the oxide film, it may be necessary to form a mask between the resist and the underlayer film to process the underlayer film. Specifically, an underlayer film for processing an oxide film, a mask for processing the underlayer film (i.e., a hardmask for the resist underlayer film), an antireflective film, and a resist may be formed sequentially on the oxide film. This multilayer structure is illustrated in FIG. 2. In this case, the most important requirements of the mask for processing the underlayer film may be etch resistance and high etch selectivity with respect to the underlayer for processing the oxide film. In addition, the mask should not be dissolved by a solvent used to form the antireflective film thereon. That is, the mask should have excellent solvent resistance.
On the other hand, in the case where a hardmask for a resist underlayer film has antireflective properties, there may be no need to form an additional antireflective film. In this case, an underlayer film for processing an oxide film, a mask for processing the underlayer film (i.e., a hardmask for the resist underlayer film), and a resist may be sequentially formed on the oxide film. This multilayer structure is illustrated in FIG. 1.
Various attempts have been made to meet the above requirements. For example, polycondensation reactants of a silane compound may be used as mask materials for processing underlayer films. However, polycondensation of the silane compound may occur in a solution state. When the polycondensation product is used to form a coating after storage for a certain time, the desired thickness of the coating may not be attained. Further, the polycondensation product may be substantially insoluble in solvents because of its high molecular weight, causing many defects to be generated. The polycondensation may be induced by silanol groups (Si—OH) present at the ends of the silane compound.